1. Field of the Invention
The invention relates to a stopper which may be used for bottles containing pharmaceutical products, particularly products intended to be subjected to a lyophilization treatment.
2. Description of the Prior Art
Various conventional stoppers are known which comprise an upper portion connected to a skirt-like member adapted to extend into the neck of a bottle up to a shoulder on the stopper. The skirts comprise a lateral opening extending from a point intermediate their length up to as far as the free end of the skirt. The stoppers additionally comprise a peripheral flange.
With stoppers of this type, in the course of treatment of a pharmaceutical product contained within the vial or bottle, the stopper is inserted within the bottle as far as the flange on the stopper such that the interior of the bottle is exposed to the atmosphere through lateral openings in the stoppers. Once the treatment of the substance within the bottle has been completed, the stopper is forced into the bottle up to the shoulder of the stopper such that the upper rim of the neck of the bottle is covered by a protective cap. When the product within the bottle is to be used, the stopper is pierced by means of a hollow needle and a liquid substance or product is injected into the bottle. The resulting mixture is drawn out of the bottle by means of suction into a syringe through a hollow needle.
Such stoppers suffer from the inconvenience that when the bottles with which they are used are small vials or the like, the substance within the bottle or vial, e.g., medication or the like, will be present in only very small quantities. In such a case, the lower end of the skirt of the stopper forms a sort of baffle when the syringe is being filled and acts to retain a portion of the product which is thus lost.
Other known stoppers avoid the above problem in that they are provided with a skirt member having a diametrical slot which extends up to the shoulder of the upper portion of the stopper. However, such stoppers are difficult to use during the stage in which the medicinal product or the like is treated within the bottle. This results since various treatment steps are performed on the bottles by means of automatic machines and the bottles are necessarily subjected to vibration. Since the stoppers are barely held within the bottles, there is a danger of them falling off prematurely which is the case with stoppers having a diametrical slot. With such stoppers, since the skirt member is in effect cut in two, it no longer exhibits the resistance necessary to maintain the stopper in the bottle neck unless it is completely inserted in the bottle.